/*
 * File     : ContiguousEnumDictionary.java
 * Created  : 28 Apr 2011
 *
 * Copyright © 2011 Matthew Wilson (mj. {my-surname} .uk {at} gmail.com)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.googlecode.dni.internal;

import java.util.Arrays;
import java.util.Map;

/**
 * <p>
 *  Implementation of {@link EnumDictionary} for a (small) contiguous range of
 *  values.
 * </p>
 *
 * @author Matthew Wilson
 */
final class ContiguousEnumDictionary extends EnumDictionary
{

    private final int offset;

    private final Enum< ? >[] values;

    /**
     * @param valueToEnumMap
     *            the map of value to enum constant
     * @param enumToValueMap
     *            the map of enum constant to value
     * @param unknown
     *            the unknown value; possibly <code>null</code>
     * @param minValue
     *            the minimum value (inclusive)
     * @param maxValue
     *            the maximum value (inclusive)
     */
    ContiguousEnumDictionary( final Map< Integer, Enum< ? > > valueToEnumMap,
                              final Map< ? extends Enum< ? >, Integer > enumToValueMap,
                              final Enum< ? > unknown,
                              final int minValue,
                              final int maxValue )
    {
        super( enumToValueMap, unknown );

        this.offset = minValue;
        this.values = new Enum< ? >[ maxValue - minValue + 1 ];

        if ( unknown != null )
        {
            Arrays.fill( this.values, unknown );
        }

        for ( Map.Entry< Integer, Enum< ? > > entry : valueToEnumMap.entrySet() )
        {
            this.values[ entry.getKey() ] = entry.getValue();
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Enum< ? > enumForValue( final int value )
    {
        int index = value - this.offset;
        if ( index < 0 || index >= this.values.length )
        {
            return getUnknown();
        }

        return this.values[ index ];
    }

}
